Method of making a customizable electrical article

ABSTRACT

A lead frame assembly comprises a stamped and formed lead frame having spaced pairs of electrical terminals and other contact sections. Severable sections initially interconnect potential electrical circuit sections of the lead frame separating the lead frame into separate metal members defining discrete electrical circuits if severed. A dielectric covering is molded over the lead frame exposing the pairs of terminals and other contact sections for termination or electrical engagement. Openings are formed in the housing exposing the severable sections of the lead frame for severing, to be selectively severed creating separate electrical circuit sections, or to be retained unsevered, as desired. After the molding of the covering over the lead frame, the article thus fabricated can be customized by selective severing and connecting of components as desired. Thus a method has been described for making a customizable lead frame assembly.

REFERENCE TO RELATED APPLICATIONS

This is a division of application Ser. No. 807,775 filed Nov. 12, 1985now U.S. Pat. No. 4,673,837 which is a continuation of application Ser.No. 609,166 filed May 11, 1984 now abandoned.

FIELD OF THE INVENTION

This invention relates to lead frame assemblies and more particularly tolead frame assemblies having electrical circuit paths therein.

BACKGROUND OF THE INVENTION

Conventional DC motor brush housings comprise carbon brushes that arespring biased against a commutator of the rotor and are mounted on aprinted circuit or wiring board or a molded dielectric housing member.Lead wires for connection to an exterior power supply are hand solderedto circuit paths on the PCB or to posts secured in the molded housingmember. Leads of capacitors and inductors for noise suppression are alsohand soldered to circuit paths or posts and the metal brush holders withthe capacitors being connected to ground that is generally a metalhousing member in which the PCB or brush housing is mounted, the metalhousing member containing a bearing in which the shaft of the rotor ismounted. These operations require numerous steps of handling,orientation of the PCB or housing member and the various components andhand soldering is required because of the irregular nature of thecomponents and the small size of the PCB or housing member. Theseoperations result in increased labor costs.

SUMMARY OF THE INVENTION

According to the present invention, a lead frame assembly for formingmotor brush assemblies comprises a stamped and formed lead frame havingpotential electrical circuit sections initially integrallyinterconnected by severable sections. The lead frame has electricalengagement or contact sections such as spaced pairs of electricalterminals for termination to electrical power wires and lead wires ofelectrical components such as capacitors and inductors, if desired, andincluding plate contact sections and a ground contact. Severing of theseverable sections which interconnect the potential electrical circuitsections would separate the lead frame into separate metal membersdefining actual electrical circuits. A dielectric covering is moldedover the lead frame with the electrical terminals and other contactsections being accessibly exposed for termination or electricalengagement means and electrical load means and openings are located inthe housing member exposing the severable sections of the lead frame forsevering. Certain ones of the severable sections may be selectivelysevered after the housing member is secured around the lead framecreating separate electrical circuit sections, or they may be retainedunsevered as desired leaving the electrical circuit sectionsinterconnected. The lead frame assembly may be on a continuous strip ofassemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a stamped and formed lead frame.

FIG. 2 is a view similar to FIG. 1 showing a dielectric housing membermolded onto the lead frame forming a lead frame assembly.

FIG. 3 is a view similar to FIG. 2 showing a partly-assembled motorbrush assembly with electrical power wires, a capacitor, an inductor anda metal brush holder terminated to the lead frame assembly and partsexploded therefrom.

FIG. 4 is a top plan view of FIG. 3 of a motor brush assembly in anassembled condition.

FIG. 5 is a perspective view of the motor brush assembly secured in ametal housing member.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a lead frame assembly 10 that is stamped and formed from ametal strip having desirable spring and electrical characteristics andwhich is disposed between carrier strips 12 and 14 by metal strips 16and 18 which are in turn connected to cross strips 20 and 22. Holes 24are located in carrier strips 12 and 14. Metal strips 16 and 18 extendinto plate sections 26 which in turn extend into a substantiallycircular section 28 around a large central aperture 29; recesses 30 arelocated in plate sections 26.

Electrical terminals 32,34,35 extend outwardly in the same directionfrom plate section 26 and circular section 28. Electrical terminals 32face each other in spaced associated pairs whereas electrical terminals34,35 are disposed in pairs with one spaced associated pair 34 locatedon one side of circular section 28 and two pairs 35 located on the otherside. Electrical terminals 32 are smaller than electrical terminals34,35 and the terminating sections of terminals 32, 34,35 have slotsextending thereinto thereby defining electrical terminals of theinsulation displacement type which are of known construction.

A ground contact 36 extends outwardly from circular section 28 betweenadjacent pairs of terminals 35. First serverable sections 37 and secondservable sections 38 are located in circular section 28, with servablesections 37 between electrical terminals 32 on one side of circularsection 28 between each of the pairs of electrical terminals 35 on theother side of circular section 28. Severable sections 37,38 remainunsevered until after a dielectric housing member is molded onto leadframe 10 to lend support to lead frame 10 prior to the moldingoperation.

While only one lead frame 10 is shown in FIG. 1, other lead frames willbe present between carrier strips 12 and 14 to form a continuous stripof lead frames which are carried by carrier strips 12 and 14 into aconventional mold so as to mold a dielectric covering such as dielectrichousing member 40 thereon as shown in FIGS. 2 through 5. The material ofdielectric housing member 40 has suitable dielectric material andstrength characteristics, and housing member 40 is molded over leadframe 10 so that it extends outwardly beyond the general outer peripherythereof. Severable sections 37,38 are thus located inwardly from thegeneral outer surface of housing member 40 and also remote fromterminals 32,34,35. Slots 42 are located in housing member 40 throughwhich the terminating sections of electrical terminals 35,35 extend andthe terminating sections of electrical terminals 32 are disposed inalignment with slots 44 in walls 46 which form component-receivingcavities. Circular wall 48 extends around large central aperture 29 andoutwardly from the top surface of housing member 40 and surrounds anopening that extends therethrough.

Parallel wall members 50 extend outwardly from circular wall 48 alongplate sections 26 and they have channels 52 on the inside wall surfacesthat are in communication with recesses 30 in plate sections 26.Recesses 54 are located in the edge of housing member 40 at thelocations of metal strips 16, 18. Recesses 56 are also located in theedge of housing member 40 on each side of a C-shaped strain reliefmember 58. Posts 57 extend from housing member 40 proximate recesses 56and in a direction opposed from terminals 34, around which power wireleads 68 are to be wrapped, as seen in FIGS. 3 and 4.

After the housing members 40 have been molded to lead frames 10, thecontinuous strip of lead frames can be reeled onto a reel member fromwhich they can be fed into a component inserting machine (not shown) orfed from the molding operation to the component inserting machine whichwill insert components and power lead wires into the electricalterminals as well as clinch brush holder members onto the lead frames.

In assembly, the lead wires of capacitors 60 are terminated in the slotsof electrical terminals 35 while inductors 62 are disposed in thecavities formed by walls 46 and lead wires thereof are terminated in theslots of electrical terminals 32 as shown in FIGS. 3, 4, and 5. Lugs 64of metal brush holders 66 extend along channels 52 between wall members50 and they are bent into electrical engagement with exposed platesections 26 in the bottom surface of housing member 40 thereby securingbrush holders 66 in mechanical and electrical engagement between wallmembers 50 (not shown in the drawings). Insulated lead wires 68 havetheir ends terminated in the slots of electrical terminals 34 and arethen disposed in respective recesses 56 and in strain relief member 58.

A motor brush assembly is thereby formed and can now be severed fromcross strips 20,22 by severing metal strips 16 and 18 in recesses 54whereafter the motor brush assembly can be secured in a metal housingmember 70 which includes a bearing member 74 in alignment with theopening defined by circular wall 48 and an opening 72 in which strainrelief member 58 is located to permit lead wires 68 to extend outwardlytherefrom. Although not shown in the drawings, ground contact 36electrically engages metal housing member 70 to form a ground connectiontherewith.

Severable sections 37,38 are exposed in first and second openings 39,39A respectively in housing member 40 as shown in FIG. 4 with openings39,39A being wider than severable sections 37,38. The severable sections37 disposed between terminals 35 in which capacitors 60 are terminatedwill be severed whereas the severable sections 38 disposed betweenelectrical terminals 32 will be severed if inductors 62 are terminatedtherein. After severable sections 37 are severed, lead frame 10 becomesseparated into separate electrical sections, with ones of associatedpairs of terminals 35 being part of a single electrical circuit sectioncontaining ground contact 36 and the others thereof being part ofrespective others of the separate electrical sections containingrespective plate sections 26 and both of terminals 32 and one ofterminals 34; and if severable sections 38 are severed, lead frame 10becomes separated into further electrical sections each containing oneof terminals 32 and one of terminals 34. The use of inductors 62 inconjunction with capacitors 60 is more effective in noise suppression.

A motor brush assembly has been disclosed that utilizies a stamped andformed lead frame to which has been molded a dielectric housing memberforming a lead frame assembly which includes electrical terminals forterminating lead wires of capacitors and inductors and power lead wires,and the housing member has cavities in which the inductors are disposed.

We claim:
 1. A method of forming a lead frame assembly comprising thesteps of:forming an integral lead frame from metal sufficiently thickwithstand handling after forming, said lead frame having a general outerperiphery having a plurality of openings located inwardly from saidgeneral outer periphery defining integrally joined metal sections, saidintegral lead frame including formed thereon a plurality of electricalengagement sections each of which is adapted to be electrically engagedby a respective electrical conductor means, and said integral lead framefurther including a sufficient number of severable sections located atselected locations inwardly from said general outer periphery and remotefrom said electrical engagement sections so that severing thereof wouldseparate said integral member into separate metal members at least twoof which each include at least two said electrical engagement sectionsand define electrical circuit paths; securing a dielectric covering oversaid integral lead frame and extending at least outwardly to saidgeneral outer periphery thereof and around substantial portions of saidmetal sections exposing at least said electrical engagement sections andincluding a general outer surface disposed outwardly from said severablesections, whereby a lead frame assembly is fully fabricated; andlocating and severing at least an appropriate one of said severablesections thereby forming at least two separate electrical circuits eachhaving at least two said electrical engagement sections, whereby a fullyfabricated lead frame assembly is capable of being customized afterfabrication thereof by selective severing of said severable sections. 2.A method of forming an electrical article for electrically connecting anelectrical power supply means and at least one electrical load meanscomprising the steps of:forming an integral lead frame having a generalouter periphery and having a plurality of metal sections each includingat least two contact sections formed therein thereby defining potentialcircuit sections, said plurality of metal sections being initiallyinterconnected only by severable sections located inwardly from saidgeneral outer periphery of said lead frame and remote from said contactsections; and molding a dielectric covering onto said lead frame andextending at least outwardly to said general outer periphery thereof andaround substantial portions of said interconnected metal sections withsaid contact sections being exposed to be electrically connected to saidpower input means and said load means, and said covering including ageneral outer surface disposed outwardly from said severable sectionsand having molded therein openings exposing said severable sections andhaving dimensions wider than said severable sections such that saidseverable sections are severable therewithin to form at least twoelectrically separate metal members from said metal sections defining atleast two discrete electrical circuits each having at least two saidcontact sections for electrically interconnecting said power supplymeans and a said load means, whereby an electrical article is fullyfabricated and is adapted to be customized remote from the fabricationsite by selective severing of said severable sections.
 3. A method asset forth in claim 2 further including after said molding step the stepsof selecting at least one of said severable sections to remain unseveredand severing the remaining others of said severable sections.